Electromagnetic coupling devices enable energy to be transferred between components of a system via interacting electric and magnetic fields. These interactions are quantified using coupling coefficients. The capacitive coupling coefficient is the ratio of the per unit length coupling capacitance, Cm, to the geometric mean of the per unit length capacitances of the two coupled lines, Cl. Similarly, the inductive coupling coefficient is the ratio of the per unit length mutual inductance, Lm, to the geometric mean of the per unit length inductances of the two coupled lines, Ll.
FIG. 1 shows a conventional broadside coupler in a space having x, y, and z orientations, where the two broadest faces of two adjacent printed circuit board conductor lines A and B are electromagnetically coupled having a distance D in between. FIG. 2 shows an edge coupler in a space having x, y, and z orientations, where the narrow faces of two conductors A and B on the same layer are coupled having a distance D in between.
Conventional coupling devices suffer from deficiencies in several areas. The coupling devices exhibit significant variations in the capacitive coupling coefficient due to manufacturing tolerances in the line geometry and in the relative position of the two coupled lines (“x,y,z variations”). Furthermore, in common manufacturing practices, the width of conductors is subject to variations of between +/−0.5 and +/−1.0 mils, the relative alignment of conductor layers within a printed circuit board (PCB) is subject to variations of +/−5 mils (x,y axis), the distance between conductor layers can vary by +/−2 mils (z axis), and the location of holes for guide pins is subject to +/−4 mil variations (x,y axis). Therefore, conventional couplers are too sensitive to misalignment to be used in computer systems.
The present invention addresses these and other deficiencies of conventional couplers.